岩石裂隙水-岩作用机制与力学行为研究

Study on water-rock interaction mechanisms and mechanical behaviors of single rock fractures

水-岩作用是导致裂隙岩体发生灾变的主要原因之一,其中的关键科学问题是准确预测裂隙岩体力学性质在水-岩作用下的时空演化规律。首先给出岩石裂隙水-岩力学、物理、化学作用的基本概念,并通过理论推导和试验研究,揭示3种水-岩作用对岩石裂隙力学行为的影响规律与内在机制。岩石裂隙有效应力系数的物理意义为其内部的空腔率,给出基于常规力学参数的岩石裂隙有效应力系数计算公式。岩石裂隙水-岩物理作用的主要机制是对基本摩擦角以及接触凸起体强度的降低。岩石裂隙的水-岩化学作用与溶液pH值密切相关,酸性溶液对岩石裂隙剪切参数的弱化效应最为显著,其次是碱性溶液和中性溶液。最后,给出考虑水-岩作用效应的岩石裂隙抗剪强度准则,并简要讨论其在实际工程中的应用前景。

Water-rock interaction is one of the main reasons triggering engineering disasters in or on fractured rocks,and the key scientific problem is to accurately predict the spatio-temporal evolution behaviors of fractured rocks under water-rock interaction.The introduction of water into rock fractures modifies the mechanical properties of rock fractures through mechanical,physical and chemical interactions between water and rock minerals,and the basic concepts of water-rock mechanical,physical and chemical interactions in rock fractures are firstly presented.The effects of the three types of water-rock interactions on mechanical behaviors of rock fractures are studied using theoretical and experimental methods.The physical meaning of the effective stress coefficient in a rough rock fracture is understood as the void ratio,and a new expression of effective stress coefficient only including a few common mechanical parameters is proposed.The water-rock physical interaction induces reductions in basic friction angle and asperity strength.Water-rock chemical interaction is strongly related to pH of chemical solutions.The acidic solution has the most significant weakening effect on the shear parameters of rock fractures,followed by alkaline solutions and neutral solutions.Finally,a complete form of fracture shear criterion considering water-rock interaction is proposed,and its implications in practical rock engineering is briefly discussed.